Airbnb hosts with more than one property make up a substantial portion of the company’s revenue, according to a new report released by the American Hotel & Lodging Association, which has vigorously opposed the company's efforts to expand in cities across the country.

Titled, "From Air Mattress To Unregulated Business," the report is the latest salvo in a between Airbnb, which argues that its hosts are using Airbnb to make supplemental income, and the hotel industry, which argues that the site facilitates illegal hotels that skirt city regulations.

The report analyzed data from Airbnb listings in 12 major cities over a 13-month period. Among these listings, rentals that are available 360 days, which the study refers to as "full-time operators," accounted for almost 30% of Airbnb’s revenue. Hosts with more than one listing on the site made up almost 40% of Airbnb’s revenue.

Airbnb has argued that its site is used mostly by hosts who treat it as casual supplemental income, focusing on the small number of listings by hosts with more than one property on its site. In December, for instance, the company released data on its New York listings that showed that 95% of its entire-home hosts (as opposed to hosts who rent a bedroom or a shared room) have only one listing.

In a statement to Fast Company, an Airbnb spokesperson argued that the data used in the study is flawed. "Many hosts have listings that are labeled available but are only occasionally rented," he wrote, adding, "Airbnb is succeeding for the very simple reason that our hosts—the vast majority of whom are middle class people sharing their homes in order to create supplemental income—provide guests authentic, transformative experiences."

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